I've build the ZOB and used the recommended DFR8s.This speaker first came out thin sounding and very bass shy. After some measurements and tweaking the adjustable slot the bass output came up but I'm not satisfied yet.

No matter what kind of music (** see references at the bottom) I play the bass output is several dBs too low. I'm used to an open baffle bass system so I'm not asking for boom bass from a reflex system.

As I'm using a mac mini booted into Windows where Foobar is running as mediaplayer I used the software equalizer within Foobar to make a BSC (+5dB below 440 Hz). I'm using an external non oversampling USBDAC of my own design (the very best digital dac I ever auditioned... yes, my own children are the best in class...)

With this compensation in the bass region this loudspeaker is indeed something very special. They present a left to right wall image reproduction and the ZOBs disappear in this image field.

Huge amount of details are presented totally effortless and the ZOBs sound very analog if you know what I mean!? I now understand why Steve compare them with electrostatic speakers like the Acoustat.I just want to play music music music and the vacuum cleaner can stay in the closet a day or two longer...

But for now I've to investigate the reason for this speaker not having the nice bass Steve is writing about without using the BSC.

No, I first used some temporary material (soft foam) and later changed it into a sealing made of rubber. It's thin (1/16) so it does not add the suggested distance (that should be included in the original design in the first place if needed IMO).

That said I'm happy to hear the bass level is gone up quite a bit but not enough IME.So I've added a passive BSC today and removed the software-based BSC. I now have plenty of nice fast bass now. :)The cost is of course I need more power to drive the speaker but no big deal.

I don't have the hammer effect in the low register as I've from my CS2 clones but the ZOB is the clear winner in coherency for now. That said I'm not done tuning my CS2s but I'm skeptical that I reached the same performance as the ZOB in this category!

I need further listening before I'll a final conclusion about this speaker system. But, I'm deeply impressed about their performance taken the low price into account.

Is it possible that the drivers are still a little shy of a sufficient break-in period?

Maybe after running them for a couple more weeks, things might "gel" a bit better. My experience has been that almost all small drivers require a substantial break-in, unlike many larger drivers which generally respond well to a day-long romp or two.

After hooking up my PP1CS tube amps I've removed the BSC. The passive BSC suck out the magic of this speaker IME.

After the sealing of the speaker using rubber tape I'm satisfied with the bass response. It can't compete with my CS2 clones using two 15" Alpha 15a drivers then it comes to moving air but the ZOB sounds just wonderful as it is now.

I am right in the middle of building the enclosures now.....what exactly did you seal with rubber tape and why did you need to do it? Would you suggest some kind of sealing that is not mentioned in the plans or white papers? Would some kind of silicone sealing of the box joints (as the resonator box was glued and screwed together) have possibly eliminated the need for rubber tape (post assembly)? I had planned on lining the resonator box with felt also. Did you do that?

Wakanda: I'll try the broadcast system using my CS2 clones as the broadcast speakers.

Big L: I had screwed the front baffle to the cabinet and used the rubber sealing in between to make the box air tight. I did this because I want to hear the speaker before spending time and money on the finish (read paint and veneer).

Oh , I see what you meant now. Since my listening room is about 11'x12' , i am hoping to be able to use the speaker without augmentation , but of course am leaving my options open on sub or miked box as you are about to try. Could you share any listening impressions now that you are using tube amps ? Other than the lowest bass notes (which we all knew we were not going to get anyway without some kind of augmentation, are you happy with the rest of the range of the speaker?

I recently built a WO32 and used black 3/4 inch wide foam tape (from local hardware) to seal the top to the bottom assembly. It compressed evenly under pressure from the screws, made a nice tight seal and looked great.